How many photons will a molecule of water have when it turns into energy?

I know the question, Oristar. (It's right there!)

Not sure I understand it.

And I do not have a clue about its answer.

By what process could one convert water into energy?

1) calculate total energy to needed to melt ice
2) calculate energy per photon
3) calculate number of photons...

like this...

*** 1 ***
assuming all the photons are absorbed....
heat required to melt ice = energy of all the photons.
4.0x10^2 g x 334 J/g = energy of photons.
1.34x10^5 J = energy of photons.

*** 2 ***
then...for a single photon...
E = hc/L = 6.626x10^-34 J s x (3.00x10^8 m/s) / (660 nm x 1m/10^9nm) = 3.01x10^-19 J

ie... 3.01x10^-19 J/photon.

*** 3 ***
1.34x10^5 J x (1 photon / 3.01x10^-19J) = 4.4x10^23 photons


Therefore:


4.0x10^2 g x (1 mole / 18.0g) x (6.022x10^23 molecules / mole) = 1.34x10^25 molecules of water

then...
1.34x10^25 molecules of water / 4.4x10^23 photons = 30 molecules of water per photon.



“By what process could one convert water into energy?”

Someday someone will invent a mill, steam engine or turbine.

Mills, steam engines and turbines do not convert water into energy.

Yes you are correct that such converting would never happen.

To convert a molecule of water into photons, simply let it meet its antimolecule and both will be annihilated into photons (energy). Making antimatter is a frontier in particle physics.

Thank you for the reply.

But 1) is wrong. The correct calculation is to use Einstein's mass-energy equation: E = mc^2. The m in the equation refers to the mass of a molecule of water, c is speed of light and E is the total energy of the molecule.

Since your premise 1) is not correct, you got an erroneous result of the calculation.

I haven't found the data about the mass of a molecule of water.

Ignoring the second law of thermodynamics, equate the energy of fusion of water to hu, as in E=hu (Planc's law) and count your photons. Of course you'll have to define the frequency)

Rap